1.
Drug
–
A drug is any substance that, when inhaled, injected, smoked, consumed, absorbed via a patch on the skin, or dissolved under the tongue, causes a physiological change in the body. In pharmacology, a drug, also called a medication or medicine, is a chemical substance used to treat, cure, prevent. Traditionally drugs were obtained through extraction from plants, but more recently also by organic synthesis. Pharmaceutical drugs may be used for a duration, or on a regular basis for chronic disorders. Another major classification system is the Biopharmaceutics Classification System and this classifies drugs according to their solubility and permeability or absorption properties. Psychoactive drugs are chemical substances that affect the function of the nervous system, altering perception. They include alcohol, a depressant, and the nicotine and caffeine. These three are the most widely consumed psychoactive drugs worldwide and are also considered recreational drugs since they are used for rather than medicinal purposes. Other recreational drugs include hallucinogens, opiates and amphetamines and some of these are used in spiritual or religious settings. Some drugs can cause addiction and all drugs can have side effects, excessive use of stimulants can promote stimulant psychosis. Many recreational drugs are illicit and international such as the Single Convention on Narcotic Drugs exist for the purpose of their prohibition. The transitive verb to drug arose later and invokes the psychoactive rather than properties of a substance. A medication or medicine is a drug taken to cure or ameliorate any symptoms of an illness or medical condition, the use may also be as preventive medicine that has future benefits but does not treat any existing or pre-existing diseases or symptoms. In the United Kingdom, behind-the-counter medicines are called pharmacy medicines which can only be sold in registered pharmacies and these medications are designated by the letter P on the label. The range of medicines available without a prescription varies from country to country, medications are typically produced by pharmaceutical companies and are often patented to give the developer exclusive rights to produce them. Those that are not patented are called generic drugs since they can be produced by other companies without restrictions or licenses from the patent holder, pharmaceutical drugs are usually categorised into drug classes. A group of drugs will share a chemical structure, or have the same mechanism of action. Another major classification system is the Biopharmaceutics Classification System and this groups drugs according to their solubility and permeability or absorption properties

2.
Dopamine
–
Dopamine is an organic chemical of the catecholamine and phenethylamine families that plays several important roles in the brain and body. It is an amine synthesized by removing a carboxyl group from a molecule of its precursor chemical L-DOPA, dopamine is also synthesized in plants and most multicellular animals. In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons to send signals to nerve cells. The brain includes several distinct dopamine pathways, one of plays a major role in reward-motivated behavior. Most types of rewards increase the level of dopamine in the brain, other brain dopamine pathways are involved in motor control and in controlling the release of various hormones. These pathways and cell groups form a system which is neuromodulatory. Outside the central system, dopamine functions primarily as a local chemical messenger. With the exception of the vessels, dopamine in each of these peripheral systems is synthesized locally. Several important diseases of the system are associated with dysfunctions of the dopamine system. Parkinsons disease, a condition causing tremor and motor impairment, is caused by a loss of dopamine-secreting neurons in an area of the midbrain called the substantia nigra. Its metabolic precursor L-DOPA can be manufactured, and in its pure form marketed as Levodopa is the most widely used treatment for the condition. There is evidence that schizophrenia involves altered levels of dopamine activity, similar dopamine antagonist drugs are also some of the most effective anti-nausea agents. Restless legs syndrome and attention deficit hyperactivity disorder are associated with decreased dopamine activity, dopaminergic stimulants can be addictive in high doses, but some are used at lower doses to treat ADHD. A dopamine molecule consists of a structure with one amine group attached via an ethyl chain. As such, dopamine is the simplest possible catecholamine, a family that includes the neurotransmitters norepinephrine and epinephrine. The presence of a ring with this amine attachment makes it a substituted phenethylamine. Like most amines, dopamine is an organic base, as a base, it is generally protonated in acidic environments. The protonated form is highly water-soluble and relatively stable, but can become oxidized if exposed to oxygen or other oxidants, in basic environments, dopamine is not protonated

3.
Jmol
–
Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D

4.
Ephedrine
–
Ephedrine is a medication and stimulant. It is often used to prevent low blood pressure during spinal anesthesia and it has also been used for asthma, narcolepsy, and obesity but is not the preferred treatment. It is of benefit in nasal congestion. It can be taken by mouth or by injection into a muscle, vein, onset with intravenous use is fast, while injection into a muscle can take 20 min, and by mouth can take an hour for effect. When given by injection it lasts about an hour and when taken by mouth it can last up to four hours, common side effects include trouble sleeping, anxiety, headache, hallucinations, high blood pressure, fast heart rate, loss of appetite, and inability to urinate. Serious side effects include stroke, heart attack, and abuse, while likely safe in pregnancy its use in this population is poorly studied. Use during breastfeeding is not recommended, ephedrine works by turning on the α and β adrenergic receptors. Ephedrine was first isolated in 1885 and it is on the World Health Organizations List of Essential Medicines, the most effective and safe medicines needed in a health system. It is available as a generic medication, the wholesale cost in the developing world is about 0.69 to 1.35 USD per dose. In the United States it is not very expensive and it can normally be found in plants of the Ephedra type. Dietary supplements that contain ephedrine are illegal in the United States, an exception is when used in traditional Chinese medicine. Both ephedrine and pseudoephedrine increase blood pressure and act as bronchodilators, ephedrine promotes modest short-term weight loss, specifically fat loss, but its long-term effects are unknown. Methylxanthines such as caffeine and theophylline have an effect with ephedrine with respect to weight loss. This led to creation and marketing of compound products, one of them, known as the ECA stack, contains caffeine and aspirin besides ephedrine. It is a popular supplement taken by bodybuilders seeking to cut body fat before a competition, as a phenethylamine, ephedrine has a similar chemical structure to amphetamines and is a methamphetamine analogue having the methamphetamine structure with a hydroxyl group at the β position. The most popular method for reducing ephedrine to methamphetamine is similar to the Birch reduction, in that it uses anhydrous ammonia, the second-most popular method uses red phosphorus, iodine, and ephedrine in the reaction. Through oxidation, ephedrine can be synthesized into methcathinone. Ephedrine is listed as a table-I precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs, ephedrine may be quantified in blood, plasma, or urine to monitor possible abuse by athletes, confirm a diagnosis of poisoning, or assist in a medicolegal death investigation

5.
Substituted amphetamine
–
The compounds in this class span a variety of pharmacological subclasses, including stimulants, empathogens, and hallucinogens, among others. Some of amphetamines substituted derivatives occur in nature, for example in the leaves of Ephedra and these have been used since antiquity for their pharmacological effects. Amphetamine was first produced at the end of the 19th century, by the 1930s, amphetamine and some of its derivative compounds found use as decongestants in the symptomatic treatment of colds and also occasionally as psychoactive agents. Their effects on the nervous system are diverse, but can be summarized by three overlapping types of activity, psychoanaleptic, hallucinogenic and empathogenic. Various substituted amphetamines may cause these actions either separately or in combination, amphetamines are a subgroup of the substituted phenethylamine class of compounds. Substitution of hydrogen results in a large class of compounds. Natives of Yemen and Ethiopia have a tradition of chewing khat leaves to achieve a stimulating effect. The active substances of khat are cathinone and, to a lesser extent, amphetamine was first synthesized in 1887 by Romanian chemist Lazăr Edeleanu, although its pharmacological effects remained unknown until the 1930s. MDMA was produced in 1912 as an intermediate product, however, this synthesis also went largely unnoticed. In the 1920s, both methamphetamine and the dextrorotatory optical isomer of amphetamine, dextroamphetamine, were synthesized and this synthesis was a by-product of a search for ephedrine, a bronchodilator used to treat asthma extracted exclusively from natural sources. Over-the-counter use of substituted amphetamines was initiated in the early 1930s by the pharmaceutical company Smith, Kline & French, as a medicine for colds and nasal congestion. Subsequently, amphetamine was used in the treatment of narcolepsy, obesity, hay fever, orthostatic hypotension, epilepsy, Parkinsons disease, alcoholism, the reinforcing effects of substituted amphetamines were quickly discovered, and the misuse of substituted amphetamines had been noted as far back as 1936. During World War II, amphetamines were used by the German military to keep their tank crews awake for long periods and it was noticed that extended rest was required after such artificially induced activity. The widespread use of substituted amphetamines began in postwar Japan and quickly spread to other countries, modified designer amphetamines gained popularity since the 1960s, such as MDA and PMA. In 1970, the United States adopted the Controlled Substances Act that limited non-medical use of substituted amphetamines, street use of PMA was noted in 1972. MDMA emerged as a substitute to MDA in the early 1970s, american chemist Alexander Shulgin first synthesized the drug in 1976 and through him the drug was briefly introduced into psychotherapy. Recreational use grew and in 1985 MDMA was banned by the US authorities in an emergency scheduling initiated by the Drug Enforcement Administration, since the mid-1990s, MDMA has become a popular entactogenic drug among the youth and quite often non-MDMA substances were sold as ecstasy. Ongoing trials are investigating its efficacy as an adjunct to psychotherapy in the management of treatment-resistant post-traumatic stress disorder

6.
Cathinone
–
Cathinone /ˈkæθᵻnoʊn/ is a monoamine alkaloid found in the shrub Catha edulis and is chemically similar to ephedrine, cathine, methcathinone and other amphetamines. It is probably the main contributor to the stimulant effect of Catha edulis, Cathinone differs from many other amphetamines in that it has a ketone functional group. Other phenethylamines that share this structure include the stimulants methcathinone, MDPV, mephedrone, Khat has been cultivated in the Horn of Africa and Arabian Peninsula region of the world for thousands of years. It is most commonly chewed for the effect it produces. The active ingredient was first proposed in 1930, when cathine was identified as a predominant alkaloid in the plant. Cathine was thought to be the active ingredient in khat until the 1960s. In 1975, the United Nations Narcotic Laboratory analyzed khat leaves from Yemen, Kenya and Madagascar and found the presence of a different alkaloid, Cathinone is a similar molecule to cathine, but is much more abundant in younger plants. This finding caused scientists to speculate about whether cathinone was the active ingredient in khat. A study was conducted in 1994 to test the effects of cathinone, six volunteers who had never chewed khat were given an active khat sample and a cathinone-free placebo sample. The researchers analyzed the participants’ moods, activity levels and blood pressure before and this analysis showed that cathinone produced amphetamine-like symptoms, leading the researchers to confirm that cathinone, not cathine, is the active ingredient in khat leaves. Over 20 million people in the Arabian Peninsula and East Africa chew khat leaves daily and it is an important piece of the culture and economy in this region, especially in Ethiopia, where khat is said to have originated, Kenya, Djibouti, and Yemen. Men usually chew it during parties or other social gatherings while smoking cigarettes, farmers and other workers also use khat in the afternoon to reduce fatigue and hunger as the day goes on. It functions like the caffeine in a cup of coffee as an anti-fatigue drug. Students and drivers have known to use it to stay alert for longer periods of time. In order to produce its effects, khat leaves should be chewed fresh. The fresh leaves have a concentration of cathinone. Waiting too long after cultivation to chew the leaf will allow the cathinone to break down into its less potent form, because of the need for quick chewing, it is a habit that has historically been prevalent only where the plant grows. However, in the recent years with improvements in road and air transport, the cultivation of khat in Yemen is a highly profitable industry for farmers

7.
Adamantane
–
Adamantane is a colorless, crystalline chemical compound with a camphor-like odor. With a formula C10H16, it is a cycloalkane and also the simplest diamondoid, Adamantane molecules consists of four connected cyclohexane rings arranged in the armchair configuration. It is unique in that it is rigid and virtually stress-free. A boat-shaped configuration can also exist, Adamantane is the most stable among all the isomers with formula C10H16, which include the somewhat similar twistane. The spatial arrangement of atoms in the adamantane molecule is the same as in the diamond crystal. This motivates the name adamantane, which is derived from the Greek adamantinos, the discovery of adamantane in petroleum in 1933 launched a new field of chemistry dedicated to studying the synthesis and properties of polyhedral organic compounds. Adamantane derivatives have found application as drugs, polymeric materials. The possibility of the existence of a hydrocarbon with the C10H16 formula, Decker called this molecule decaterpene and was surprised that it had not been synthesized yet. The first attempted laboratory synthesis was made in 1924 by German chemist Hans Meerwein using the reaction of formaldehyde with diethyl malonate in the presence of piperidine. Instead of adamantane, Meerwein obtained 1,3,5, 7-tetracarbomethoxybicyclononane-2, 6-dione, later, another German chemist D. Bottger tried to obtain adamantane using Meerweins ester as precursor. However, the product, tricyclo- decane ring system, was again an adamantane derivative, other researchers attempted to synthesize adamantane using phloroglucinol and derivatives of cyclohexanone, but also with failure. Adamantane was first synthesized by Vladimir Prelog in 1941 from Meerweins ester, the process was impractical, as it contained five stages and had a yield of about 0. 16%. However, it was used to synthesize certain derivatives of adamantane. Prelogs method was refined in 1956, the decarboxylation yield was increased by the addition of the Heinsdecker pathway and the Hoffman reaction that raised the total yield to 6. 5%. This method increased the yield to 30–40% and provided a source of adamantane. The adamantane synthesis yield was increased to 60% and 98% by ultrasound. Today, adamantane is an chemical compound with a cost of about $1 a gram. All the above methods yield adamantane as a polycrystalline powder, using this powder, single crystals can be grown from the melt, solution, or vapor phase

8.
Theobromine
–
Theobromine, formerly known as xantheose, is a bitter alkaloid of the cacao plant, with the chemical formula C7H8N4O2. It is found in chocolate, as well as in a number of foods, including the leaves of the tea plant. It is classified as an alkaloid, which also include the similar compounds theophylline and caffeine. The compounds differ in that caffeine has a methyl group. Theobromine is a slightly water-soluble, crystalline, bitter powder, theobromine is white or colourless, but commercial samples can be yellowish. It has a similar to, but lesser than, that of caffeine in the human nervous system. Theobromine is an isomer of theophylline, as well as paraxanthine, theobromine is categorized as a dimethyl xanthine. Theobromine was first discovered in 1841 in cacao beans by Russian chemist Alexander Voskresensky, synthesis of theobromine from xanthine was first reported in 1882 by Hermann Emil Fischer. Theobromine is the primary found in cocoa and chocolate. Cocoa powder can vary in the amount of theobromine, from 2% theobromine, there are usually higher concentrations in dark than in milk chocolate. Theobromine can also be found in small amounts in the nut, the guarana berry, yerba mate. 28 grams of milk chocolate contains approximately 60 milligrams of theobromine, cocoa beans naturally contain approximately 1% theobromine. Cleavage of the ribose and N-methylation yields 7-methylxanthosine, 7-Methylxanthosine in turn is the precursor to theobromine, which in turn is the precursor to caffeine. Theobromine is a vasodilator, a diuretic, and heart stimulant and it is not currently used as a medicinal drug. Because of this effect, and its ability to dilate blood vessels. In the human body, theobromine levels are halved between 6–10 hours after consumption, theobromine has also been used in birth defect experiments involving mice and rabbits. A decreased fetal weight was noted in rabbits following forced feeding, birth defects were not seen in rats. Possible future uses of theobromine in such fields as cancer prevention have been patented, theobromine has also been shown to improve the microhardness of tooth enamel which could potentiality increase resistance to tooth decay

9.
Bromantane
–
Bromantane is an atypical psychostimulant and anxiolytic drug of the adamantane family that is used in Russia in the treatment of neurasthenia. Because of its aspects, bromantane has sometimes been described instead as an adaptogen. In the 1960s, the adamantane derivative amantadine was developed as a drug for the treatment of influenza. Other adamantane antivirals subsequently followed, such as rimantadine and adapromine, amantadine was then developed and introduced for the treatment of Parkinsons disease due to its ability to increase dopamine levels in the brain. It has also notably since been used to alleviate fatigue in multiple sclerosis. It was found to produce more marked and prolonged psychostimulant effects than the other adamantanes, the drug was notably given to soldiers in the Soviet and Russian militaries to shorten recovery times after strong physical exertion. After the break-up of the Soviet Union in 1991, bromantane continued to be researched and characterized but was limited in use to sports medicine. Bromantane was eventually repurposed in 2005 as a treatment for neurasthenia and it demonstrated effectiveness and safety for the treatment of the condition in extensive, including large-scale clinical trials, and was approved for this indication in Russia sometime around 2009. The therapeutic effects of bromantane in asthenia are said to onset within 1- to 3-days and it has been proposed that the combination of psychostimulant and anxiolytic activity may give bromantane special efficacy in the treatment of asthenia. In a large-scale, multi-center clinical trial of 728 patients diagnosed with asthenia, the impressiveness were 76. 0% on the CGI-S and 90. 8% on the CGI-I, indicating broadly-applicable, high effectiveness. The therapeutic benefit against asthenia was notably observed to still be present one-month after discontinuation of the drug, quality of life was significantly increased by bromantane, and this increase remained at one-month after withdrawal of bromantane. 3% of patients experienced side effects, none of the effects were serious. Bromantane was also noted to normalize the sleep-wake cycle, the authors concluded that in daily dose from 50 to 100 mg is a highly effective, well-tolerated and drug with a wide spectrum of clinical effects. Therefore, this drug could be recommended for treatment of disorders in neurological practice. Bromantane is described primarily as a psychostimulant and anxiolytic. It is also said to possess antiasthenic properties, bromantane is reported to improve physical and mental performance, and hence could be considered a performance-enhancing drug. It has also found to increase sexual receptivity and proceptivity in rats of both sexes, which was attributed to its dopaminergic actions. It has been proposed that bromantane may suppress prolactin levels by virtue of its properties as well

10.
Cathine
–
Cathine, also known as d-norpseudoephedrine and -norpseudoephedrine, is a psychoactive drug of the phenethylamine and amphetamine chemical classes which acts as a stimulant. Along with cathinone, it is naturally in Catha edulis. It has approximately 10-14% the potency of amphetamine, like amphetamines, cathinone, and ephedrine, cathine acts as a norepinephrine releasing agent. It also acts as a releasing agent to a lesser extent. Cathine is one of the four stereoisomers of phenylpropanolamine, the World Anti-Doping Agencys list of prohibited substances bars cathine in concentrations of over 5 micrograms per milliliter in urine. Cathine is a Schedule III drug under the Convention on Psychotropic Substances, in the United States, it is classified as a Schedule IV controlled substance. In Australia, Cathine is officially a schedule 4 drug but is not yet available or approved for any use, in Hong Kong, cathine is regulated under Schedule 1 of Hong Kongs Chapter 134 Dangerous Drugs Ordinance. Unlawful possession is punishable by fines and imprisonment. L-Norpseudoephedrine, an enantiomer Phenylpropanolamine Catha edulis Cathinone Methcathinone Ephedra sinica Ephedrine Pseudoephedrine Phenethylamine Amphetamine Methamphetamine

11.
Adenosine receptor
–
The adenosine receptors are a class of purinergic G protein-coupled receptors with adenosine as endogenous ligand. In humans, there are four types of adenosine receptors, each is encoded by a separate gene and has different functions, although with some overlap. The adenosine A1 receptor has been found to be throughout the entire body. This receptor has a function on most of the tissues in which it is expressed. In the brain, it slows metabolic activity by a combination of actions, presynaptically, it reduces synaptic vesicle release while post synaptically it has been found to stabilize the magnesium on the NMDA receptor. Specific A1 antagonists include 8-Cyclopentyl-1, 3-dipropylxanthine, and Cyclopentyltheophylline or 8-cyclopentyl-1, 3-dipropylxanthine, tecadenoson is an effective A1 adenosine agonist, as is selodenoson. The A1, together with A2A receptors of endogenous adenosine play a role in regulating myocardial oxygen consumption, stimulation of the A1 receptor has a myocardial depressant effect by decreasing the conduction of electrical impulses and suppressing pacemaker cell function, resulting in a decrease in heart rate. This makes adenosine a useful medication for treating and diagnosing tachyarrhythmias and this effect on the A1 receptor also explains why there is a brief moment of cardiac standstill when adenosine is administered as a rapid IV push during cardiac resuscitation. The rapid infusion causes a momentary myocardial stunning effect, in normal physiological states, this serves as a protective mechanism. Theophylline and caffeine are nonselective adenosine antagonists that are used to stimulate respiration in premature infants, adenosine receptors play a key role in the homeostasis of bone. The A1 receptor has shown to stimulate osteoclast differentiation and function. Studies have found that blockade of the A1 Receptor suppresses the osteoclast function, as with the A1, the A2A receptors are believed to play a role in regulating myocardial oxygen consumption and coronary blood flow. The activity of A2A adenosine receptor, a G-protein coupled receptor family member, is mediated by G proteins that activate adenylyl cyclase and it is abundant in basal ganglia, vasculature and platelets and it is a major target of caffeine. The A2A receptor is responsible for regulating blood flow by vasodilating the coronary arteries, which increases blood flow to the myocardium. Just as in A1 receptors, this serves as a protective mechanism. Specific antagonists include istradefylline and SCH-58261, while specific agonists include CGS-21680, the role of A2A receptor opposes that of A1 in that it inhibits osteoclast differentiation and activates osteoblasts. Studies have shown it to be effective in decreasing inflammatory osteolysis in inflamed bone and this role could potentiate new therapeutic treatment in aid of bone regeneration and increasing bone volume. This integral membrane protein stimulates adenylate cyclase activity in the presence of adenosine and this protein also interacts with netrin-1, which is involved in axon elongation

12.
Norepinephrine
–
Norepinephrine, also called noradrenaline or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as a hormone and neurotransmitter. Norepinephrine is also the international nonproprietary name given to the drug, regardless of which name is used for the substance itself, parts of the body that produce or are affected by it are referred to as noradrenergic. In the brain, norepinephrine is produced in closely packed brain cell neurons or nuclei that are small yet exert powerful effects on brain areas. The most important of these nuclei is the locus coeruleus, located in the pons, regardless of how and where it is released, norepinephrine acts on target cells by binding to and activating noradrenergic receptors located on the cell surface. The general function of norepinephrine is to mobilize the brain and body for action, norepinephrine release is lowest during sleep, rises during wakefulness, and reaches much higher levels during situations of stress or danger, in the so-called fight-or-flight response. In the brain, norepinephrine increases arousal and alertness, promotes vigilance, enhances formation and retrieval of memory, a variety of medically important drugs work by altering the actions of norepinephrine systems. Norepinephrine itself is used as an injectable drug for the treatment of critically low blood pressure. Beta blockers, which some of the effects of norepinephrine, are frequently used to treat glaucoma, migraine. Alpha blockers, which counter a different set of effects, are used to treat several cardiovascular. Alpha-2 agonists often have an effect, and are commonly used as anesthesia-enhancers in surgery. Many important psychiatric drugs exert strong effects on systems in the brain. Norepinephrine is a catecholamine and a phenethylamine and its structure differs from that of epinephrine only in that epinephrine has a methyl group attached to its nitrogen, whereas the methyl group is replaced by a hydrogen atom in norepinephrine. The prefix nor- is derived as an abbreviation of the word normal, norepinephrine is synthesized from the amino acid tyrosine by a series of enzymatic steps in the adrenal medulla and postganglionic neurons of the sympathetic nervous system. These amino acids are found in nearly every protein and, as such, are provided by ingestion of protein-containing food, phenylalanine is converted into tyrosine by the enzyme phenylalanine hydroxylase, with molecular oxygen and tetrahydrobiopterin as cofactors. Tyrosine is converted into L-DOPA by the tyrosine hydroxylase, with tetrahydrobiopterin, O2. L-DOPA is converted into dopamine by the enzyme aromatic L-amino acid decarboxylase, dopamine is then converted into norepinephrine by the enzyme dopamine β-monooxygenase, with O2 and ascorbic acid as cofactors. Norepinephrine itself can further be converted into epinephrine by the enzyme phenylethanolamine N-methyltransferase with S-adenosyl-L-methionine as cofactor, in mammals, norepinephrine is rapidly degraded to various metabolites. The initial step in the breakdown can be catalyzed by either of the monoamine oxidase or COMT